A sign with the names of the Boston Marathon bombing victims is placed at a makeshift memorial near the site of the blasts on Sunday in Boston. / Kevork Djansezian, Getty Images

by Laura Petrecca, USA TODAY

by Laura Petrecca, USA TODAY

As the events surrounding the Boston Marathon bombings unfolded, social media were a great supplier of information for many - and a source of inaccurate information and frustration for some.

A quarter of Americans got information about the devastating explosions and the hunt for the bombers on social networking sites such as Facebook and Twitter, according to a report out Tuesday from the Pew Research Center. Young Americans in particular kept up-to-date through social media. Slightly more than half (56%) of an 18-to-29 year subgroup polled by Pew got bombing-related news through social networking sites.

Those sites offer a convenient way to get news, especially since many users are constantly on them, says Michael Dimock, director of Pew's public opinion and polling project.

They "are on Facebook, and the information is just flowing at them," he says.

Yet while social network updates can feed a news-hungry audience with relevant and interesting updates, they can also breed false information, says social media expert Dave Kerpen, CEO of the social media marketing firm Likeable Media.

As people on social media, including journalists, sometimes conveyed wrong information last week, "it was challenging to know what (sources) to trust," he says.

Even Kerpen accidentally shared incorrect information. He can't recall what it was -- he deleted it from his Twitter feed and apologized for posting it.

Last week, after CNN and the Associated Press wrongly reported that the suspects were in custody, many others picked up the news.WCVB-TV Boston, crediting the AP with the news, wrongly said that an arrest was "imminent." It was retweeted 87 times

On Monday, social media site Reddit acknowledged its role in helping to disseminate false information, saying, "Some of the activity on reddit fueled online witch hunts and dangerous speculation."

Reddit also said it apologized to the family of missing Brown University student Sunil Tripathi, who was misidentified on social media as a bombing suspect.

Another challenge for social media users in the wake of a tragedy: figuring out what is appropriate to share and what is not. For instance, some social media users posted graphic images of bombing victims.

Others posted ordinary personal updates, not related to the explosions, on the day they happened and afterwards. That could be seem insensitive, Kerpen says.

"If you're on Facebook and Twitter to get news on the bombing suspects and you see a company posting a sale or a friend posting a picture from a kid's birthday party, neither is relevant to you," he says.

He notes, though, that some people think it's fine to post unrelated content when it comes to terrorism as a way to show that an act designed to terrorize won't stop everyday life.

About one in 10 Pew respondents (12%) said social media sites offered an "easy" and "convenient" way to follow the Boston Marathon news. Nearly the same number (11%) said social networks provided "fast" and "up-to-date" information.

Six percent said they used social media to keep up with friends and family who were in Boston. And 6% said they went to such sites to get different perspectives or because they provided "uncensored" information.

While social media kept Americans informed, many people also turned to traditional sources to keep up on the events of last week.

TV was the most widely used source of information about the bombings, according to Pew, used by 80% of Americans. Four in 10 kept up via radio reports, and three in 10 read newspapers.

Nearly half got news online or on a mobile device.

Overall, 63% of Americans said they followed the bombing-related updates very closely, making it one of the biggest news stories since 2001, Pew said. News events that drew more public interest were the 9/11 attacks, Hurricane Katrina, the 2008 economic downturn and the 2002 sniper shootings near Washington, D.C.